Nine Inch Nails/Ghostbusters mashup. More stuff over at stereogum.com. The Bloc Party one is particularly recommended.
Watched Napoleon Dynamite last night, which totally blew me away. Just a lovely lovely film (even if you watch a lot of it with hands over eyes, thinkin 'nooo... it's all going to go horribly wrong..'). Immediately went back and watched it again with the commentary on, and was delighted to see how much of was based on the writers' (there's two of them, so the apostrophe's correct - as was that one) own experiences. And has the best SexyDancing scene I have ever seen on screen. It's that good.
Over at moebius rex they've got a 50 Cent/Jungle Book mashup which might just be the finest thing I've ever heard - about four songs down. Reduced 50 Cent to the sad little children's entertainer he actually is, whilst being simulataneously being a rather wizard bit of production. Someone has spent a lot of time and energy to make a silly man sound even sillier, and that has to be applauded.